SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
of blood in airways and lung tissue, and reducing the likelihood of this may be the
best justification for using F.
Treatment with 0.5mg/kg furosemide iv 24 hr before strenuous exercise, when
combined with controlled access to water (6ml/kg every 4 hrs with the last drink 8 hrs
before racing), attenuated the severity of EIPH in 6 racehorses. However, because
the number of horses studied was small, a larger clinical study is needed to further
evaluate whether this treatment protocol consistently attenuates the severity of
EIPH.
Other Pharmacologic Strategies There are many other practices that are utilized in
the cause of managing EIPH. They include pro-coagulants, nitric oxide analogs,
phosphodiesterase type 5 inhibitors, antihypertensive agents and other diuretics,
bronchodilators, and controlled access to water. None have been shown to be
effective in mitigating EIPH severity. However, their use continues in many places.
Before these treatments can be dismissed, further work needs to be done under field
conditions. Most of the research on EIPH treatments to date has been conducted
using treadmills. As the following table shows, the severity of EIPH is usually much
less during treadmill exercise when compared to that which occurs during racing or
hard training. Consequently, it is much harder to show a scientifically significant
effect when the severity of the control state is not very marked. Therefore, there may
be some agents that so effectively mitigate EIPH when the non-treated condition is
much more severe than is observed on a treadmill. Drugs for which additional
evaluation is most indicated are the nitric oxide analogs and phosphodiesterase type
5 inhibitors.
Horse
ΔBAL rbc/µl
treadmill
TBE EIPH
track
score
treadmill track
1 3 2 3,275 12,250
2 2 2 9,454 5,250
3 2 4 11,157 1,519,550
4 1 2 15,439 19,500
5 1 2 58,000 81,650
6
1
2
4,070
5,675
Table: Tracheobronchoscopic (TBE) EIPH score and differences between pre- and post-exercise bronchoalveolar lavage fluid
red blood cell numbers (ΔBAL rbc) per µl of recovered fluid for 6 horses following supramaximal treadmill and racetrack
exercise under controlled conditions.
In otherwise healthy horses, bronchodilators do not dilate airways during exercise.
There is a maximum diameter to which airways can dilate and the endogenous
sympathetic nervous system is more than capable of inducing maximum dilation.
Nasal Strips
The application of nasal strips has been shown to reduce the severity of EIPH and it
is unclear as to why more horses don’t wear them when racing and breezing. The
mechanism of action is related to reduced resistance to airflow which in turn means
that the inspiratory pressures generated are not as great with the result that the
transmural pressure across the pulmonary capillary-alveolar interface are not as
high, and EIPH is reduced accordingly.
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